Maseb
I can see why Alex asked the question in the first place.
Comparing, and keeping tabs on how others are developing is, as far as I know, really common and doesn’t mean someone isn’t straight.
In my case, the first person I remember being attracted to was a girl in my class in the last year of primary school. This would be UK school year 6, equivalent to US 5th grade, ages 10-11. Of course, at that age, I didn’t suggest we did anything together. I also don’t think I have looked at a guy and had the same reaction.
But, next, in time, was when another boy suggested we rub each other through our trousers and I liked the idea. Of course, the trousers didn’t stay on very long and we ended up masturbating each other. I really enjoyed it, and we repeated it several times after that.
Then I ended up having sex with a girl and it was like WOW - I liked that even more.
At the moment I have a g/f and I am having sex exclusively with her. If we were to split up, I would be looking for another girl, rather than a guy, for the next relationship but, if opportunities to get off with another guy came up in between I would probably do it: it’s fun, it’s harmless, why not?
So despite the WOW factor for straight sex, it didn’t make me look back on mutual masturbation with a guy and think it was a passing phase or something that was no longer of any interest. My take is that cumming feels really good and, though straight sex would be what I would choose, it still feels good however it happens whether it’s with a girl, with a guy or just masturbating and I am not going to discount any of them.
Some people also make a distinction between romance and sex, i.e. they may describe themselves as heteroromantic but bisexual. To me, that raises the question of what do we want a label or identity for? Maybe it is just to communicate but if the important thing is “Who should I be looking for as a potential partner, and where would I find them”, then concentrating on that may make things seem simpler.